C h a p t e r 1 9
Disorders of Cardiac Function
475
General Manifestations, Diagnosis, and
Treatment
It is increasingly common for congenital heart defects
to be diagnosed prenatally.
69
In this case, the infant can
be evaluated shortly after birth to confirm the diagnosis
and develop a treatment plan. Reliable transabdomi-
nal diagnostic images of the fetal heart can be obtained
as early as 16 weeks of gestation, and recently, accu-
rate trans-vaginal images have been obtained as early
as 11 to 14 weeks of gestation. Among the disorders
that can be diagnosed with certainty by fetal echocar-
diography are AV septal defects, hypoplastic left heart
syndrome, aortic valve stenosis, hypertrophic cardiomy-
opathy, pulmonic valve stenosis, and transposition of
the great arteries. Disorders that result in an abnormal
four-chamber view, an image typically obtained during
routine prenatal ultrasonography, are the most likely to
be detected.
69
In the postnatal period, congenital heart defects may
present with numerous signs and symptoms, most com-
monly a murmur audible on auscultation. Some defects,
such as patent ductus arteriosus and small ventricular
septal defects, close spontaneously. In other less-severe
defects, there may be no obvious signs and symptoms
and the disorder may be discovered during a routine
health examination. Cyanosis, pulmonary congestion,
cardiac failure, and decreased peripheral perfusion are
the major concerns in children with more severe defects.
Such defects often cause problems immediately after
birth or early in infancy. The child may exhibit cyano-
sis, respiratory difficulty, and fatigability, and is likely to
have difficulty with feeding and failure to thrive. Heart
failure manifests itself as tachypnea or dyspnea at rest or
on exertion. For the infant, this most commonly occurs
during feeding. Recurrent respiratory infections and
excessive sweating may also be reported.
70
The infant
whose peripheral perfusion is markedly decreased may
be in a shocklike state.
A generalized cyanosis that persists longer than
3 hours after birth suggests congenital heart disease. An
oxygen challenge (administration of 100% oxygen for
5 to 10 minutes) can help to determine whether con-
genital heart disease is present in a cyanotic newborn.
70
Because infant cyanosis may appear as duskiness, it is
important to assess the color of the mucous membranes,
fingernails, toenails, tongue, and lips. Several programs
have instituted routine pulse oximetry screening for all
newborns.
71
Pulmonary congestion in the infant causes
an increase in respiratory rate, orthopnea, grunting,
wheezing, coughing, and crackles. A chest radiograph
can quickly differentiate infants who have reduced pul-
monary vascular markings (densities) from those who
have normal or increased markings.
The treatment plan usually includes supportive
therapy (e.g., digoxin, diuretics, and feeding supple-
mentation) designed to help the infant compensate for
the limitations in cardiac reserve and to prevent com-
plications. Surgical intervention often is required for
severe defects. It may be done in the early weeks of
life or, conditions permitting, delayed until the child is
older. Children with structural congenital heart disease
and those who have had corrective surgery may have
a higher-than-expected risk for development of infec-
tive endocarditis. Prophylactic antibiotic therapy before
dental procedures or other periods of increased risk for
bacteremia is suggested for children with certain types
of heart defects or surgical procedures.
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Children with congenital heart disease also experi-
ence a higher than expected incidence of developmental
delays.
73,74
A characteristic pattern of combined disabili-
ties in the areas of visual motor integration, language,
motor skills, attention, executive function and behavior
has been described in multiple research studies.
73–75
In
an effort to promote early detection of developmental
delays and appropriate intervention, the American Heart
Association and the American Academy of Pediatrics
issued a joint guideline statement in 2012 suggest-
ing systematic surveillance, screening, and evaluation
throughout childhood to assess academic, behavioral,
psychosocial and adaptive functioning.
76
Early detec-
tion of developmental problems will direct interventions
which can prevent or reduce long-term issues known to
have a profoundly negative impact on quality of life and
ability to achieve optimum potential in adulthood.
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Types of Defects
Congenital heart defects can affect almost any of the
cardiac structures or central blood vessels (Fig. 19-21).
Defects include communication between heart cham-
bers, interrupted development of the heart chambers
or valve structures, malposition of heart chambers and
great vessels, and altered closure of fetal communica-
tion channels. The particular defect reflects the embryo’s
stage of development at the time it occurred. It is com-
mon for multiple defects to be present in one child and
for some congenital heart disorders, such as tetralogy of
Fallot, to involve several defects.
Patent Ductus Arteriosus.
Patent ductus arteriosus
results from persistence of the fetal ductus beyond the
prenatal period.
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In fetal life, the ductus arteriosus is
the vital link by which blood from the right side of the
heart bypasses the lungs and enters the systemic circula-
tion (Fig. 19-21G). After birth, this passage no longer
is needed, and it usually closes during the first 24 to 72
hours of life. The physiologic stimulus and mechanisms
associated with permanent closure of the ductus are not
entirely known, but the fact that infant hypoxia predis-
poses to a delayed closure suggests that the increase in
arterial oxygen levels that occurs immediately after birth
plays a role. Additional factors that contribute to clo-
sure are a fall in endogenous levels of prostaglandins
and adenosine and the release of vasoactive substances.
After constriction, the lumen of the ductus becomes per-
manently sealed with fibrous tissue within 2 to 3 weeks.
Ductal closure may be delayed or prevented in very pre-
mature infants, probably as a result of a combination of
factors, including decreased medial smooth muscle in the
ductus wall, decreased vasoconstriction response to oxy-
gen, and increased circulating levels of prostaglandins,
